Multi-parametric Analysis of Blood Pressure and Heart Rate Coupling: Characteristic Patterns of Tilt Test Responses

The laws governing blood pressure and heart rate coupling contain significant information about underlying physiological mechanisms of cardiovascular response to both internal and external stresses. Detailed investigation of these mechanisms requires a better understanding of the short-term physiological dynamics observed during orthostatic tilt test. Revealing characteristic profiles of tilt test responses could be essential for a variety of applications ranging from basic physiological studies to the differential diagnostics in patients with orthostatic disorders suffering from spontaneous syncope episodes of unknown etiology. Six different indicators of blood pressure versus heart rate coupling during both the entire tilt test procedure as well as its supine and orthostatic phases have been considered in this study. Empirical classification patterns indicate that several considered indices exhibit significant discrepancies between the test phases as well as between the patients and normal subjects involved in the study.